Conventionally, it has been well known a cutting apparatus having a portable circular saw device as a cutting device that is detachably mounted on a fixed surface plate as a base section. Such a cutting apparatus has been disclosed in U.S. Pat. No. 4,587,875. In the cutting apparatus, a base plate is movably fixed to a base section. The base plate is formed with a saw blade slot allowing a saw blade of a cutting device to pass therethrough. The cutting device having a motor and a cutting unit is fixed to the base plate. The base plate has a pair of planar surfaces, namely, a bottom surface and an upper surface. The saw blade slot is surrounded by the base plate. A protruding portion of the saw blade that protrudes from the bottom surface side of the saw blade slot can be protected by being covered with a saw blade guard. The saw blade guard is connected to a linkage mechanism. When the cutting device is pivotally moved in association with pivotal movement of the base plate so that the saw blade is positioned closer to a workpiece, the protruding portion of the saw blade that is covered with the saw blade guard is gradually reduced. The protruding portion of the saw blade is gradually exposed to the atmosphere, and thus, the workpiece can be cut by the exposed portion of the saw blade.